National Key Laboratory of Crop Genetic Improvement, Key Laboratory of Horticultural Plant Biology of the Ministry of Education, Huazhong Agricultural University, Wuhan 430070, China.
J Exp Bot. 2011 May;62(8):2899-914. doi: 10.1093/jxb/erq463. Epub 2011 Jan 31.
Arginine decarboxylase (ADC) is an important enzyme responsible for polyamine synthesis under stress conditions. In this study, the gene encoding ADC in Poncirus trifoliata (PtADC) was isolated and it existed as a single-copy member. Transcript levels of PtADC were up-regulated by low temperature and dehydration. Overexpression of PtADC in an Arabidopsis thaliana ADC mutant adc1-1 promoted putrescine synthesis in the transgenic line and the stomatal density was reverted to that in the wild type. The transgenic line showed enhanced resistance to high osmoticum, dehydration, long-term drought, and cold stress compared with the wild type and the mutant. The accumulation of reactive oxygen species (ROS) in the transgenic line was appreciably decreased under the stresses, but ROS scavenging capacity was compromised when the transgenic plants were treated with the ADC inhibitor D-arginine prior to stress treatment. In addition, the transgenic line had longer roots than the wild type and the mutant under both normal and stressful conditions, consistent with larger cell number and length of the root meristematic zone. Taken together, these results demonstrated that PtADC is involved in tolerance to multiple stresses, and its function may be due, at least partly, to efficient ROS elimination and to its influence on root growth conducive to drought tolerance.
精氨酸脱羧酶（ADC）是一种在应激条件下负责多胺合成的重要酶。在本研究中，分离得到了枳（Poncirus trifoliata）中的 ADC 编码基因（PtADC），它作为单拷贝成员存在。PtADC 的转录水平受低温和脱水的上调。在拟南芥 ADC 突变体 adc1-1 中过表达 PtADC 促进了转基因株系中腐胺的合成，并且气孔密度恢复到野生型水平。与野生型和突变体相比，转基因株系对高渗、脱水、长期干旱和冷胁迫表现出更强的抗性。在胁迫下，转基因株系中活性氧（ROS）的积累明显减少，但当转基因植物在胁迫处理前用 ADC 抑制剂 D-精氨酸处理时，ROS 清除能力受损。此外，在正常和胁迫条件下，转基因株系的根比野生型和突变体更长，这与根分生组织区更大的细胞数量和长度一致。总之，这些结果表明 PtADC 参与了多种胁迫的耐受，其功能可能至少部分归因于有效清除 ROS，以及其对有利于耐旱性的根生长的影响。
